I dont know which test pipe I should order for my ap2 , my exhaust is stock , I want a test pipe that has the same diameter as my exhaust (which I dont know its diameter ) , I want to eliminate the chance of a bottle neck effect .

ScienceofSpeed Exhaust Test Pipe
http://www.scienceofspeed.com/products/exh...aust_test_pipe/

or

Berk Technology test pipe

or

?????????????????

I appreciate your help .

 

I'd like to know this as well.

 

I think the stock diameter is sixty something mm. You know that there are 70mm testpipes right? Those won't bottleneck the exhaust like you're worried about since they're bigger than stock. Invidia has a 60mm testpipe and a 70mm one you could look into.

 

stock is 63 mm

 

AFAIK, stock is 60mm. inside diameter.

 

so Berk Technology 63.5mm test pipe will be fine right ?

 

another test pipe you didn't mention OP is Invidia, they have both the 60mm and 70mm test pipes.

I ordered the 60mm one, which should come in a few days.

 

I am confused , should I order 63mm or 60mm ? .

 

If I didn't have already have a 2nd o2 bung in my header I would have gotten the SoS piece. 2 bungs FTW!

 

get a 70mm and then get a 70mm exhaust.